Conventional bicycle headlamps using an incandescent lamp receive power for providing illumination sufficient for nighttime cycling from a rotary generator, to which a rotary motion is transferred by a roller pressed against a side of a tire. This method exerts a large frictional resistance on the rotary motion, and the cyclist feels a drag while pedaling. Accordingly, cycling at night requires extra power. The conventional generator using the roller to be pressed against the side of the tire, however, must be turned on manually, and thus a trouble-free simple device has been needed.
The conventional method of pressing the roller against the side of the tire has problems. A first problem is that the roller pressed against the side of the tire while cycling at night incurs a frictional resistance on the rotary motion, causing the cyclist to feel that the pedals have become heavy.
A second problem is that illumination will decrease when cycling on a muddy road because mud getting in between the tire and the roller causes the roller to slide along the tire.
A third problem is the need to manually turn on and turn off the generator for cycling at night.
An object of the present invention is to provide a contactless, light-load bicycle headlamp and a headlamp electrical circuit that can solve the problems described above by adopting new technologies.